Pneumatic tool.



1. T. IVICGRATH. PNEUMATIC TOOL. APPilATI'oN FILED APR. 26. |911.

mme@ Apr; 30, 1918.

@a o k 'Y 154?. if) UV@ ill JOHN T. MoGrRATI-I, OJE BLOOMINGTON, ILLINOIS.

PNEUMATIG TOOL.

Specification of Letters Patent.

Patented Apr. 3U, imi.

Application led April 26, 1917. Serial No. 164,609.

thereof, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which forma part of this specification.

This invention relates to improvements in pneumatic tool devices such as hammers, chisels, riveting machines, and the like, and the invention refers more particularly to an improved valve mechanism b. which the air or other motive agent is a mitted to the cylinder and is exhausted therefrom.

The invention consists in the combination and arrangement of the parts shown in the drawings and described in the specification, and is pointed out in the appended claims.

Among the objects of the invention is to provide a novel valve mechanism by which the inlet of air is controlled to and its exhaust discharged from the cylinder of the machine in such a way that the cylinder may be completely exhausted at the end of the power stroke through relativel small exhaust ports, while at the Sametime the charge of air is retained in the cylinder a length of time suiicient` to efficiently utilize the effect of expansion thereof to operate the tool.

Figure 1 is an axial section of a pneumatic tool .embodying my invention. 4

Figs. 2 and 3 are cross sections on lines 2-2 and 3-3 respectively, of Fig. 1.

Fig. 4 is a detail of the means for locking the tool shank to the socket member.

Fig. 5 shows a modified valve. As shown in said drawings, 10 designates the barrel of the ytool which is internally bored to provide a cylinder 11 in which reciprocates a piston 12. Said piston is attached to or, made integral with'a hammer 14, composed of a hammer head and shank, and the bore of the barrel is reduced beyond the diameter of the cylinder atq15 to` such diameter that the hammer shank lits closely therein. The outer end ofthe barrel is formed to provide a socket member 16 to receivc the shank 17 of the cutting or riveting tool 18. The opposite end of the barrel is partly closed by the end wall 19 of a hollow cap' 21 that is threaded over the end of the barrel and said end wall is centrally apertured to provide a port 20. The outer end of said cap is closed by a coupling 24 that fits within and is threaded to the cap and is anged to extend over the end of the Qcap at 24. The said cap incloses a pressure chamber 23 which is in communication with a main air pipe 25 through a series of ports 22, and said pipe is provided with any usual or preferred type of operatin valve 26.

The port 20 is controlled y a valve 28 that is provided with a valve stem 29 which extends through said port 20 and into the cylinder; and the cylinder and hammer shank are centrally apertured to, provide a guide .passage to receive said stem, the stem having a close sliding fit in said passage. That portion of the stem which enters said guide passage is hollow. Said valve stem is provided between the piston and the wall 19v of the closin cap with a shoulder 31 which is engagedy the piston, when the latter moves outwardly, in a manner to lift the valve 28 oif of its seatl The valve stem is also provided inwardly beyond said shoulder with a plurality of exhaust ports 32 which are spaced both angularly about and longitudinally along the valve stem. In certain positions of the piston the ports yare within the central guide passage of the piston and hammer shank and are therefore closed, and in other positions of the piston and shank the ports 32 are uncovered so as to aord communication between the cylinder and the hollow valve stem. The inner end of the stem may be open to discharge air into the central guide passage of the piston and hammer shank and the body of the hammer shank is provided with a series of radial, angularly spaced ports 33 which, when the hammer is at its full power stroke' aord communication between said central guide passage and an exhaust space 35 within the outer end of the barrel, which space com AsoV municates with the atmosphere through la l series of radial ports 36.

The pressure chamber 23 in the'cap communicates with the cylinder 11 at a pointbelowthe inner face of the piston 12 through a port 88 formedpartly in the wall of the barrel radially exterior to the cylinder and communicating with the pressure chamber througha port 89 in the cap 21.

As herein shown, and preferably made,

the valve 28 is formed with a cylindric exvent passage 24a is provided in the'coupling,

which prevents air'locking of the valve in the event of leakage of ,air past the exteni sion 28.

The operation of the tool described is as follows:

When the operating valve 26 is opened and the cylinder and hammer occupy the position shown in Fig. 1, or any other position Lbetween this and its full stroke, air under` pressure is admitted to the cylinder through port 88 beneath the piston 12 and'forces the same,together with the hammer, outwardly. Contact of the piston with the shoulder 81 of the valve stem, in the outward movement of the piston, acts through the valve stem to.

lift the valve 28 off of its seat and to open the port 20 so that the full air pressure of the chamber 28 is exerted on the outer face of the' piston. At this time the piston has passed over the exhaust ports 82 of the valve stem and the exhaust ports 88 of the hammer are within the restricted portion 15 of the barrel, so that the air entering the outer end of the cylinder acts with its full force on the piston, and counter to the smaller pressure active against the smaller area of the inner face of the piston to move or thrust the hammer inwardly against the shank of the tool. After the piston has traveled through somewhat more than half of its stroke thel exhaust ports 82 are uncovered and the hammer is moved outwardly suiiicient to uncover the exhaust ports 88. These exhaust ports are made relatively small so that the air is gradually exhausted from the cylinder, but are made sufficiently numerous and spaced longitudinally of the valve stein so that when the piston has reached its full stroke suicient exhaust valve area is provided to lfully exhaust the air. The construction described efficiently utilizes the expansive force of the air, and at the same time provides for a complet-e clearance of the air from the cylinder before the plston is again retracted under the pressure directed against the inner face of the piston throu h the port 88. The ports 86 are sufficient y large to permit free exhaust of the air from the exhaust chamber 85 after it passes through the ports 88.

So far as the broader features of the exhaust valve mechanism are concerned, it will be understood that the same general effects may be secured by providing exhaust ports, which function as do the exhaust ports 82, of other form and in other parts of the device in a position to be controlled by the reciprocating movement of the piston' instead of placing the same in a hollow valve stem as herein shown. For instance, I may employ two or more oblong ports 82', shown .in Fig. 5 which are narrowed attheir upper ends and widest at their lower ends.

The tool shank 17 is made of an external diameter smaller than the internal diameter of the socket member 16 and is provided with spaced shoulders 40, 41, which latter fit closely in the bore of thc socket. The tool is held in place by means of short stout pins 42 which extend through radial open* ings in the socket member and enter the annular space between the reduced' part of the shank and the bore of the socket and intermediate the shoulders 40 and i1 of the shank. Said pins limit the outward movement 40f the tool when it is struck by the full force of the hammer and is not otherwise limited in its movement by its contact with the work.

. As a means for holding the limiting pins 42 in place a locking sleeve 44 is provided,

which may be madevof light sheet metal, and

' ate with a short locking pin 46 that is seated in a notch in the socket piece. The shape of the slot 45 is such that when the sleeve is placed on the socket piece the slot will pass over the locking pin 46, and by a slight angular movement of the sleeve and thereafter forcing the, sleeve outwardly the pin engages a locking notch 47 in one end of the L-shaped slot.

It is to be understood that thc structural details of the invention may be somewhat varied from those herein shown and described, and the invention is, therefore, not limited to the particular details, except as to the claims wherein they are specifically set forth, or as imposed by the'prior art.

I claim as my invention 1.. ln a pneumatic tool, a barrel formed to provide a cylinder, a differentially faced piston reciprocable in said cylinder, with sively opened during the lattery meagre means to constantly admit air from a. source under pressurev to said cylinder at the smallerl face of said piston and other means means whereby said ports are progressively opened to release pressure against said larger face of the piston during the latter part of the power stroke of the piston.

2. In a pneumatic tool, a barrel formed to provide a cylinder, a differentially faced piston -recprocable in said cylinder, with means at one end of the cylinder to constantly admit air from a source under pressure to said cylinder at the smaller face of said piston, and other means controlled by the piston to controllably admit air from said source to the cylinder at the larger face of said piston, there being a. series of exhaust ports spaced annularly around and longitudinally along the axis of said cylinder through which spent air isexhausted, with means whereby said ports are pro respart o the power stroke of said piston. f

3. In a pneumatic tool, abarrel formed to provide a cylinder, a 'dii'erentially faced piston and hammer reciprocable in said cylinder, with means to admit air from a source under pressure to said cylinder to the opposite'faces of said iston, said piston and hammer being provi ed with a central ,f the barrel when the piston is travelingi guide passage that communicates with the atmosphere throughsuitable ports, and a tubular member extending into said guide passage and provided along its length with elongated exhaust ports which are adapted to be coveredand uncoveled in the travel of said piston.

4. In a pneumatic tool, a barrel formed to provide a cylinder, a diierentially faced piston and hammer reciprocable in said cylinder, with means to admit air from a source under pressure to said cylinder at the opposite faces of the piston, said piston and hammer being provided with a central guide' passage that communicates with the atmosphere through suitable forts, a. tubular member extending into sai guide passage and provided with elongated exhaust ports which fare adapted to be progressively covered and uncovered in the travel of the piston, the said hammer shank being of smaller diameter than the piston and fitting closely in a reduced portion of the barrel, ports extending fromthe inner end of the guide passage and adapted to be closed by the wall of through the outer limits of its stroke, the barrel being provided with an exhaust chamber with which said ports communicate at tilt the end of the power stroke of the piston and with ports leading from said exhaust chamber.

5. In a pneumatic tool, a barrel having` a cylinder of unequal diameter in its length, a piston reciprocable in the larger diameter of the cylinder,-a hammer reciprocable in the smaller diameter of the cylinder and connected to the piston, av valve for controlling the flow of air to the cylinder against the larger face of the piston, there being a passage to direct the air to the cylinder against the smaller face of the piston, and

means whereby said valve is opened when the piston recedes from its power stroke, there being exhaust ports disposed longitudinally of the axis of the piston and adapted to be progressively covered and uncovered by the piston in its travel.

6. A pneumatic tool comprising a barrel having a cylinder of unequal diameter in its length, a piston reciprocable in the larger -diameter of the cylinder, a hammer connected thereto and reciprocable in the smaller diameter of the cylinder, a valve for controlling the flow of air `to the cylinder against. the larger face of the piston, with means to direct air under pressure -to the cylinder against the smaller face of the piston, said p1ston and hammer being provided with an axial guide passage, and a hollow stem connected to the valve and extending into and communicating with said passage and provided with a shoulder which is engaged by the piston to unseat the valve, and provided also with longitudinally disposed exhaust ports adapted to bel covered and uncovered by the piston in its travel.

7. A pneumatic tool comprising a barrel havinga cylinder, a diiferentially faced pisagainst the smaller face of said piston, said y piston and hammer being provided with an axial guide passage, and a hollow stem connected to the valve and d extending into said passage, with means whereby the movement of the piston controls said valve, said stem being provided with longitudinally disposed exhaust ports which are adapted to be covered and uncovered by the Vpiston in its l travel.

8. A pneumatic tool comprising a barrel having a'cylinder, a dierentially faced piston reciprocable in the cylinder,v a hammer reciprocable in the cylinder and yconnected to the piston, a valve for controlling the flow of air under pressure to the cylinder against the larger faceI of the piston, with means to direct the air under ressure to the cylinder against the smaller ace of said kio piston, said piston and hammer being provided with an axial guide passage, and a hollow stem connected to the valve and extending `into said passage, with means whereby the movement of the piston controls said valve; said stem being provided with longitudinally disposed exhaust ports 9. AA pneumatic tool comprising a barrel formedto provide a cylinder, a diiierentially faced piston and4 connected hammer reciprocable in the cylinder, a pressure chamber at one end of the barrel, there being a port affording communication between the pressure chamber and cylinder at the larger side of the piston, with a passage affording communication between the pressure chamber and said cylinder at the other face of the piston, and a valve controlling said port and provided with a hollow stem, said piston and hammer being provided with a guide opening to receive said stem, and the stein being provided with longitudinally disposed exhaust ports which are opened .and closed by the piston, with means whereby spent air is exhausted from the hollow valve stem.

10. 1n a pneumatic tool device, a cylinder, a differentially faced piston therein, there being a port through which full fluid pressure is delivered to the larger face of said piston, with a controlling valve therefor, and a passage through which fiuid is delivered at constant pressure to the smaller face of the piston, together with means to progressively release the exhaust from the cylinder toward the end of the power stroke.

of the piston and to aHord full clearance exhaust opening at the end of said power stroke.

11. 1n a pneumaticl tool device, a cylinder, a piston, a hammer operated thereby, there being a port through which full air pressure is delivered on said piston to operate the hammer, and a valve to control said port, provided with a hollow stem, the piston and hammer provided with a guide passage to receive said stem and having an exhaust opening, and the hollow stem being provided with longitudinally disposed exhaust ports which are alternately covered and uncovered by said piston. i

' 12. In a pneumatic tool device, a cylinder, a piston, aphammer operated thereby, there being a port through which full air pressure is delivered on said piston to opport, while relieving the valve of said full pressure.

13. A pneumatic tool device cdmprising a cylinder of unequal diameter in its length, a piston reciprocating in the larger diameter of the cylinder and a connected hammer shank reciprocating in the smaller diameter of the cylinder, a hollow cap applied to the end of the cylinder and having a port and inclosing a pressure chamber, a valve to control said port and provided with an axial extension, a coupling threaded to said cap and provided with a flange to closely receive said extension, there being inlet ports in said coupling for directing air under pressure to the pressure chamber radially exterior to said extension, means to operate said valve and means to exhaust air from said cylinder. Y

l14. A pneumatic tool device comprising a cylinder of unequal diameter in its length, a piston reciprocating iii the larger diameter of the cylinder and a connected hammer shank reciprocating in the smaller diameter of the cylinder, a hollow cap applied to the eiid of the cylinder and having a port and inclosing a pressure chamber, a valve to control said port and provided with an axial extension, a coupling threaded to said cap and provided with a. iange to closely receive said extension, there being inlet ports in said coupling for directing air under pressure to the pressure chamber radially extel rior to said extension, said piston provided with an axial opening and the valve being provided with a hollow, ported stem to enter said opening.

15. A pneumatic tool device comprising a cylinder, a piston reciprocating therein, there being a port through which full fluid pressure is delivered to said cylinder a ainst the piston to operate the same, a va ve to control said port, with means whereby said valve is opened by movement of the piston, and means for delivering full {iuid ressure through said port, while relieving t e valve of said full fluid pressure.

16. A pneumatic tool device comprising a cylinder, a piston reciprocating therein, said cylinder bein provided at one end with a pressure cham er, there being a ort to connect said pressure chamber to said cylinder, a valve to control said ort and a pressure pipe connected to saidp pressure chamber through passages which open into the pressure chamber radially at the sides of the center of said valve, the Wall of the pressure chamber being provided radially inside said passages with means which inclose a portion of the valve, whereby full fluid pressure may be delivered through said port, While relieving said valve of said full fluid pressure.

17. A pneumatic tool device comprisin a cylinder,-a differentially faced piston reciprocating therein, said cylinder being provided at one end with a pressure chamber, there being a port to connect said pressure chamber to said cylinder at the larger face of the piston, a valve to control said port, and a pressure pipe, connected to said pres sure chamber through a passage Which opens into the pressure chamber radially at the side of' the center of said valve, the Wall of the pressure chamber bein provided with means which inclose a portion of the valve, whereby f'ull fluid pressure may be delivered through said port, While relieving said valve of said full fluid pressure, and there being also a constantly open passage connecting said Jressure chamber to the cylinder at the smal er face of the piston. i

18. A pneumatic tool device comprising a cylinder, a piston reciprocating therein, there being a port through which full fluid pressure is delivered to said cylinder against the piston to operate the same, a valve to control said port, with means whereby said valve is opened by movement of the piston, said valve being provided with an axial extension and a flange on the Wall of the pressure chamber surrounding said extension.

19. In a pneumatic tool device, a cylinder,`

a piston therein, and a valve member provided at one end with a valve piece and With an axial extension and reciprocable in the axis of the piston, said valve member being provided on the side thereof remote from said extension With an axial stem and the stem being provided with exhaust ports disposed longitudinally of the stem.

20. In a pneumatic tool device, a cylinder, a hollow piston, and a valve member rovided with a valve face piece and with a ollow stem to enter said hollovvT piston, said stem provided with exhaust ports disposed longitudinally of said stem, and with -a shoulder adapted for engagement by a moving part of said piston.

In Witness whereof I claim the foregoing as my invention, I hereunto append my signature in the presence of tWo Witnesses at Bloomington, Illinois, this 13th day of April, 1917.

JOI-IN T. MCGRA'IH. Witnesses:

MARY C. GLEESON, A. F. DELAHUNTY. 

